Chlorinated chemicals (e.g., chlorofluorocarbons, and hydrochlorofluorocarbons) have been used in the past as solvents within a number of specialized industrial applications. For instance, chlorinated chemicals are known to be useful within cleaning applications, including dry cleaning, wherein contaminated articles are washed (e.g., immersed in or otherwise contacted) to remove the contaminant. The chlorinated chemicals can be used as liquids or vapors, and at ambient or elevated temperatures (often in cleaning applications accompanied by ultrasonic agitation). Other applications wherein chlorinated chemicals are known to be useful include using chlorinated chemicals as coating or deposition solvents, for the removal of water from substrates, as a thermal media for heat transfer applications, as a blowing agent for polymeric foams, as a fire-extinguishing agent, and as a coolant/lubricant in metal working applications.
A major concern relating to the use of such chlorinated chemicals is the tendency (especially when used at an elevated temperature) for vapor loss into the atmosphere, causing pollution. Although care can be exercised to minimize such losses (e.g., through good equipment design and vapor recovery systems), most practical applications result in the loss of at least some vapor into the atmosphere.
Popular chlorinated chemicals that have been useful in the past (e.g., as cleaning solvents) include 1,1,2-trichloro-1,2,2-trifluoroethane and 1,1,1-trichloroethane. These are useful alone or in admixture with one or more co-solvents such as aliphatic alcohols or other low molecular weight polar compounds. These particular chlorinated compounds were initially believed to be environmentally benign, but have now been linked to depletion of the earth's ozone. According to the Montreal Protocol and its attendant amendments, production of such solvents has been discontinued in the U.S. (see, e.g., P. S. Zurer, "Looming Ban on Production of CFCs, Halons Spurs Switch to Substitutes," Chemical & Engineering News, page 12, Nov. 15, 1993).
Thus, there has developed a need for substitutes or replacements for chlorinated chemicals that have been commonly used in the past. Such substitutes should exhibit one or more useful chemical or physical properties including a low ozone depletion potential, a boiling range suitable for solvent cleaning applications, and high solvency, i.e., the ability to readily dissolve or disperse organic and/or inorganic contaminants, such as water, hydrocarbon-based compounds, and fluorocarbon-based compounds. Preferably, substitutes will also be low in toxicity, have no measurable flash points (as determined by ASTM D3278-89), have acceptable thermal and chemical stability for use in a given application, and have short atmospheric lifetimes and low global warming potentials. Many compounds have been proposed as substitutes for such chlorinated compounds in a number of different uses and applications. Still, there remains a need for chemical compounds capable of replacing past commonly used chlorinated compounds and that exhibit one or more of such useful chemical or physical properties.